An elliptical galaxy is a type of galaxy with an approximately ellipsoidal shape and a smooth, nearly featureless image. They are one of the four main classes of galaxies described by Edwin Hubble in his Hubble sequence. Elliptical galaxies are the most abundant type of galaxies found in the universe, but they are frequently outshone by younger, brighter collections of stars due to their age and dim qualities. Elliptical galaxies lack the swirling arms of their more well-known siblings, spiral galaxies, and instead, they bear the rounded shape of an ellipse, a stretched-out circle. Elliptical galaxies have a broader range in size than other types of galaxies, ranging from dwarf elliptical galaxies with tens of millions of stars to supergiants of over one hundred trillion stars that dominate their galaxy clusters. Elliptical galaxies are characterized by several properties that make them distinct from other classes of galaxies. They are spherical or ovoid masses of stars, starved of star-making gases, and there is very little interstellar matter (neither gas nor dust), which results in low rates of star formation, few open star clusters, and few young stars. Elliptical galaxies are dominated by old stellar populations, giving them red colors. Elliptical galaxies are typically found in galaxy clusters and in compact groups of galaxies. Unlike flat spiral galaxies with organization and structure, elliptical galaxies usually contain little gas and dust and show very little organization or structure. The stars orbit around the core in random directions and are generally older than those in spiral galaxies since little of the gas needed to form new stars remains. Scientists think elliptical galaxies originate from collisions and mergers with spirals.